Expert: Sherry Wallin - 7/8/2010

Question
QUESTION: For the question below, I am looking for the formula on how to set the problem up and solve. Thanks!

You are standing 140 ft. from the base of a platform. The angle of elevation from your position to the top of the platform is 48 degrees. How high is the platform?

ANSWER: Courtney~
    The angle of elevation is just the angle you would look at if you were measuring from the horizontal. So you have a platform (could be a building, flagpole, tree, etc) and you want the angle that goes from the horizontal to the top of the platform. You are standing 140ft from the base of the platform meaning you are 140 ft away from the platform. You have a right triangle where 140 ft is the base of the triangle and the height is what you are looking for. So try the tan 48deg = opp/adj meaning x/140 = tan 48deg. Now solve for x getting x = 140*tan 48deg

Math Prof

---------- FOLLOW-UP ----------

QUESTION: I understand that tan=opp/adj but I don't understand where x/140=tan48deg. How do I solve for x? I like step by step instructions, so if you were able to do that, I would appreciate it. Thanks!

Answer
x/140 = tan 48 deg, how do you get x by itself? What is attached to x? 140 and how is 140 attached to x? By division. And what is the inverse operation to division? Multiplication. So multiply both sides of the equation by 140: 140*(x/140) = 140*tan 48 deg. On the left the 140's cross cancel leaving x by itself.

Math Prof